New and Novel HIV Medications

Combination antiretroviral therapy (ART) has greatly reduced HIV-associated morbidity and mortality and improved the quality of life for those living with HIV.

Advances, including new agents and novel strategies, continue to improve treatment options. Treatment guidelines have shifted away from long-established classes and regimens.^1,2 Most treatment-naive patients are initiated on 2 nucleoside reverse transcriptase inhibitors (NRTIs), plus a third drug from the integrase strand transfer inhibitor (INSTI) class, because of high rates of treatment success and tolerability. In certain clinical situations, a regimen consisting of 2 NRTIs plus a boosted protease inhibitor or non-nucleoside reverse transcriptase inhibitor (NNRTI) may be preferred. The decision about which antiretroviral regimen to choose is based on its adverse effect (AE) profile, convenience, efficacy, and genetic barrier to resistance. Factors such as comorbidities, concomitant medications, and preferences, should also be considered. Single-tablet regimens, dosed once daily, have helped in adherence and overall effectiveness.^3,4

Strategies surrounding antiretroviral regimen changes have become a major part of helping people with HIV. Treatment simplification and switch strategies have largely focused on optimizing adherence and limiting long-term toxicities in patients already controlled on ART. Carrying out such changes without doing harm (development of resistance and treatment failure) has been a high priority. Evaluating the efficacy and safety of dual (2-drug) therapy, instead of the conventional 3-drug combination, has been at the forefront of changes in philosophy.^1,2

Here is a look at several antiretroviral agents and combinations that were recently approved or are late in development, including a few dual-therapy options.

BICTEGRAVIR-EMTRICITABINE— TENOFOVIR ALAFENAMIDE (BIKTARVY)

Bictegravir is the latest second-generation INSTI coformulated with the NRTIs emtricitabine and tenofovir alafenamide (with reduced bone and renal toxicity) to form Biktarvy, a single-tablet regimen approved to treat HIV-1 in treatment-naive patients or to replace ART in those virologically controlled. Like dolutegravir, bictegravir has a high invitro barrier to resistance and remains active against many resistant strains. Biktarvy can be taken with or without food and is not recommended in patients with creatinine clearance <30 mL/min.^5,6 In 2 phase 3 clinical trials, bictegravir-emtricitabine-tenofovir once daily was compared with once-daily dolutegravir-abacavir-lami-vudine and with dolutegravir-emtricitabine—tenofovir alafenamide once daily. Bictegravir-emtricitabine- tenofovir in both trials was found to achieve viral suppression and was not inferior to both dolutegravir regimens at week 48.^6,7 Biktarvy has minimal drug interactions, with the exception of dofetilide and rifamycins. Also, oral absorption of bictegravir is reduced when it is coadministered with polyvalent cations, such as aluminum, calcium-containing antacids, and magnesium.⁵

DOLUTEGRAVIR-RILPIVIRINE (JULUCA)

To limit long-term toxicities and potential drug interactions, dual therapy has been shown to be a viable switch option for patients controlled on traditional but suboptimal triple therapy.^8,9 The FDA recently approved the first dual-therapy combination, dolutegravir-rilpivirine (Juluca), after 2 studies found the combination was not inferior to ART therapies in maintaining HIV suppression at 48 weeks. The most common adverse effects seen in studies were nasopharyngitis and headache. Drugs that increase gastric pH and that contain polyvalent cations reduce the plasma concentrations of rilpivirine significantly and should be avoided or spaced appropriately.¹⁰

DARUNAVIR-COBICISTAT-EMTRICITABINE— TENOFOVIR ALAFENAMIDE (JANSSEN THERAPEUTICS)

Darunavir-cobicistat-emtricitabine—tenofovir alafenamide (D/C/F/ TAF) is a single-tablet protease inhibitor-based regimen in development that was submitted for a new drug application (NDA) in 2017. In the AMBER and EMERALD phase 3 trials, D/C/F/TAF was found to be not inferior to the comparator regimens in both treatment-naive and -experienced patients as a switch option. Both studies showed a reduction in bone mineral density and improvements in the tubular biomarkers and proteinuria in the D/C/F/TAF group. These reductions were seen because D/C/F/TAF has the new formulation tenofovir alafenamide versus the comparator regimens that contained tenofovir disoproxil fumarate. The most common AEs seen in both studies were diarrhea, nasopharyngitis, nausea, rash, and upper respiratory infections.^11,12

IBALIZUMAB-UIYK (TROGARZO)

In March 2018, the FDA approved ibalizumab-uiyk under an orphan drug designation to treat HIV-1 infection in treatment-experienced adult patients with documented multi-antiretroviral class resistance and whose regimens have failed.¹¹ Ibalizumab-uiyk is the first novel monocolonal antibody for HIV-1. Ibalizumab-uiyk is a CD4-directed postattachment inhibitor, which acts by binding to CD4 and prevents the postattachment steps needed for HIV-1 to enter host cells.¹² Ibalizumab-uiyk is administered by a trained medical professional as an intravenous infusion over at least 30 minutes every 2 weeks. Patients must be monitored for infusion-related reactions. In a heavily treated population with multidrug-resistant HIV-1 and detectable viral load, 43% of the 40 enrolled patients who received ibalizum-ab-uiyk in conjunction with other antiretrovirals achieved treatment success.¹³ Although most adverse reactions were mild to moderate, 9 patients experienced serious adverse reactions.

DORAVIRINE (MERCK & CO, INC)

Doravirine is an NNRTI that recently submitted an NDA, including a coformulation with tenofovir disoproxil fumarate and lamivudine as a single-tablet regimen.¹⁴ It is dosed once daily, without regard for meals, and is expected to have minimal drug interaction potential.

Doravirine, plus 2 NRTIs, was shown to be not inferior to ritona-vir-boosted darunavir- and efavirenz-based regimens at achieving virologic suppression.^15,16 Doravirine appeared to have fewer neuro-psychiatric AEs and a better lipid profile than the comparator arms. There appears to be a larger potential for doravirine in treatment-experienced patients because this agent retains antiviral activity against select strains that cause resistance to NNRTIs.

CABOTEGRAVIR-RILPIVIRINE LA (VIIV HEALTHCARE)

The pharmacokinetic and pharmacodynamic properties of rilpivir-ine and the INSTI cabotegravir allow for a long-acting injectable formulation of this combination, providing a possible alternative to daily oral therapy. Cabotegravir, a potent analogue of dolutegravir, plus rilpivirine is being studied as an intermittent intramuscular injection, with an oral tablet lead-in to ensure tolerability.¹⁷ Phase 2b data demonstrated good efficacy as maintenance therapy through 96 weeks as both a monthly and bimonthly injection.¹⁸ Treatment was well tolerated across all 3 arms, with minimal complaints of injection-site reactions, and 88% of patients receiving interactive metronome therapy were happy to continue with the therapy, compared with 43% of those in the oral therapy arm. Phase 3 trials continue both monthly and bimonthly.^19-21

DOLUTEGRAVIR-LAMIVUDINE (VIIV HEALTHCARE)

Another dual-therapy option undergoing investigation is dolutegravir-lamivudine. With its high potency and genetic barrier to resistance, it has shown promising efficacy and safety data when combined with lamivudine.²² Studies are evaluating this combination for both switch strategies among patients already on ART and as initial therapy for treatment-naive patients.^23-25 The hope is that dolutegravir-lamivudine will demonstrate efficacy and safety comparable to those of the current standard of care (triple-drug therapy), potentially reducing exposure to antiretrovirals and cutting costs in the United States and worldwide.^26,27

FOSTEMSAVIR (VIIV HEALTHCARE)

Another promising option in development for patients heavily experienced in treatment is fostemsavir, a novel, orally administered entry inhibitor. This agent binds to the viral envelope protein gp120, preventing attachment to the CD4+ glycoprotein and subsequent entry into the cell.²⁸ Fostemsavir, a prodrug of temsavir, received a breakthrough therapy designation from the FDA. Phase 3 data have demonstrated significantly lower HIV RNA levels from baseline than the placebo, with 54% of patients randomized to receive the study drug achieving virologic control.²⁹ Headache and rash were the most common adverse effects, but no severe events occurred.

Saira Chaudhry, PharmD, MPh, is a clinical assistant professor at the Ernest Mario School of Pharmacy at Rutgers University in Piscataway, New Jersey, and a clinical pharmacist at Jersey Shore University Medical Center in Neptune City specializing in infectious diseases.Humberto R. Jimenez, PharmD, BCPS, AAHIVP, is a clinical assis- tant professor at the Ernest Mario School of Pharmacy at Rutgers University and a clinical pharmacist at St. Joseph’s University Medical Center in Paterson, New Jersey, specializing in infectious diseases.